1. Field of the Invention
The invention relates to an optoelectric sending and receiving apparatus for a bi-directional beam waveguide with a sender and a receiver.
2. Description of the Related Technology
DE 37 16 772 shows an optoelectrical sending and receiving apparatus. An electro-optical sender, for example a light emitting diode, and an optoelectronic receiver, for example a photodiode, are placed coaxially above each other. Coaxially located beam wave guides are located between this sender and receiver layout and a beam wave guide connecting section A hollow cylindrical beam wave guide is optically coupled to the receiver and a cylindrical beam wave guide is coupled to the sender. Special, non commercial sender and receiver semiconductors and specially adapted beam wave guides are required. The wave guides add significant expense to the apparatus. In addition, this known sender and receiver apparatus has the disadvantage that high values of the return loss .alpha. between the sender and the receiver cannot be obtained with the connection sector inserted because a gap must be maintained between the frontal surfaces of the coaxially located beam wave guides facing the beam wave guide terminal surface for the sender and the receiver, and the terminal surface of the beam wave guide connecting sector. Return loss values higher than 20 to 25 dB cannot be obtained due to geometry dependent conditions. However, the application of optoelectronic sender and receiver apparatus in transmission systems requires return losses higher than 35 dB.
Taper coupler configurations with fiber connectors are known. Mounting of plugs on these connectors reflections appear at the glass air transitions in the plug when mounted on these connectors. The reflections arrive by a branching point at the receiver. Such known configurations are not suitable for most applications.
Another possibility consists of the use of branching points which operate in a wave length selective manner and are equipped with connectors for beam wave guide plugs. No uniform terminal devices are possible with these configurations. Two emitter diodes with different wave lengths are required, thereby increasing the expense of the solution.